Conventional acoustic pianos such as a grand piano and an upright piano are configured by a great number of components. As the assembly of such components is very complex, the assembly work takes a long time. In particular, an action mechanism arranged in correspondence with each key requires many components, and hence the assembly work thereof is very complex.
For example, in an action mechanism described in Japanese Unexamined Patent Publication no. 2005-292361, a plurality of components operate together and the movement of the key by key depression and key release is transmitted to a hammer. In particular, in a support assembly configuring one part of the action mechanism, various components operate in combination. The support assembly includes not only a mechanism for realizing string hitting by the hammer according to the key depression, but also an escapement mechanism for releasing the force transmitted to the hammer by the operation of the key immediately before the string hitting. This mechanism is an important mechanism for realizing the basic operation of the acoustic piano. In particular, in the grand piano, a double escapement mechanism in which a repetition lever and a jack are combined is generally adopted.
The operation of the action mechanism provides a feeling (hereinafter referred to as “touch feeling”) to the finger of the player through the keys. In particular, the configuration of the support assembly greatly influences the touch feeling. For example, the touch feeling by the operation of the escapement mechanism is called “let-off”.